Mechanism for operating slide-valves



(ModeL) J. W. SARGENT.

MECHANISM FOR OPERATING SL'IDE VALVES.

N0. 318,037. Patented May 19, 1885.

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UNTTED STATES PATENT OFFICE.

JOHN WARREN SARGENT, OF GAMBRIDGEPOET, MASSACHUSETTS.

MECHANISM FOR OPERATING SLIDE-VALVES.

SPECIFICATION forming part of Letters Patent No. 318,037, dated May 19, 1885.

Application filed November 24, 1884. (ModeL) To aZZ whom it may concern:

Be it known that I, JOHN WARREN SAR- GENT, of Oambridgeport, in the county of MiddleseX, of the Commonwealth of Massachusetts, have invented a new and useful Improvement in Mechanism for Operating the Slide Valve or Valves of a Steam-Engine Cylinder; and I do hereby declare the same to be described in the following specification and represented in the accompanying drawings, of which- Figure l is aplan or top view, Fig. 2 a side elevation, and Fig. 3 an end View, of mechan' ism embracing my invention, the nature of which is defined in the claim hereinafter presented. Fig. i is a side View of the main cam B, and Fig. 5 is a side view of the cutoff cam O, of such mechanism.

With my invention the steam can be cut off at any suitable part of the stroke of the piston, in order for such steam to act expansively, as may be required, the cutoff mechanism being variable for such purpose. The cut-off cam, hereinafter set forth, may be adjusted by means, as hereinafter described, to effect a constant degree of cutting off of the steam for each stroke of the piston of the enginecylinder, this constant degree being varied as the cam may be further adjusted on the shaft.

In the drawings, A denotes the shaft of a steam-engine, such shaft having upon it two cams, B and O, the first of which is the main and the second the cut-off cam, they being shown in separate side views in Figs. 4 and 5.

The main cam B is, by clamp-screws a in its hub 22 or by a key or keys, to be firmly fixed on the shaft A, alongside of and at a proper distance from the cut-ofi' cam O, which is revoluble on the shaft, so as to be adjustable either way thereon relatively to the main cam; but by the main cam on one side and a collar, 0, fastened to the shaft on the other, is prevented from moving endwise on the shaft.

The cam O has to its hub lugs d d, carrying pins 6 e, from which in practice the links from a governor are to extend. This governor,when used, is to turn the cam 0 more or less either way, as may be required,relatively to the cam B. As the cutting off of the steam is effected by means of the cut-off cam, the governor will control the cut-off.

The governor above referred to is to be of the class of centrifugal governors in which the balls or weights revolve with and about the main or driving shaft of the steam -engine. Examples of such kinds of governors are shown in the United States Patents Nos. 1,179 and 204,924, and in Reissue No. 8,433.

When a governor is not used in connection with the cam G for giving a variable cut-off, the said cam may be either firmly fastened to the shaft, or it may beprovided with means of adjusting it thereon, or enabling it to be ad justed or turned and fixed relatively to the cam B.

The main cam B is situated directly between two parallel levers, D D, fulcrumed at or near their lower ends to abedplate, E. Alongside of each of the saidlevers is another but shorter lever, F,the cam G beingimmediately between the two levers F.

At their upper ends all the levers are connected to an extensible and contractile link, G, to which they are jointed, the joint-pins of such link and levers being shown at g g. This link is formed in two sections, it h, which lap on each other, and are provided with keys or wedges '5, arranged in them as shown, for moving one or the other of them. They also have screws and nuts Zfor clamping them together, such screws going through slots in the two sections. The link G is thus made, in order for it to be contracted in length, as may be necessary to bring the rollers of the levers into proper contact with the main cam as such cam and rollers may become worn.

The two leversF at their lower parts are connected by another such link, H, which is jointed to them and to the connecting-rod I, for working the valve or valves of the enginecylinder, 850. In each of the levers is a friction roller or wheel, in, for the cam next to such levers to bear against.

From the above it will be seen that as the two cams revolve with and are turned by the shaft A a vibratory movement will be im parted to the levers D, link G, levers F, link H, and-connecting rod I, whereby the valve or valves will be intermittently reciprocated across the induction and eduction ports of the engine-cylinder, so as to alternately open and close the said induction-ports.

The action of the main cam B on the levers D through the levers F,moving on the cut-off earn 0 as a fulcrum, and link I, is to give the valve or valves a constant lead or opening of steam-port, a constant compression or closing of exhaustport, and a constant release or opening of exhaust --port for each end of the cylinder, this constant action being variable only by a readjustment of the main cam on the shaft.

The action of the cutoff cam C on the levers F, turning on the pins 9 g as fulcra, through the connectingrod I, is to give the valve or valves an automatic variable cut-off under different loads of the engine, when the cam C may be operated by a governor, or aconstant cut-off, provided such cam be firmly clamped on the shaft. The movement which the cam O imparts to the valve or valves is just sufficient to close the steam-port at one end of the cylinder at a time, and at the same time not enough to choke the exhaust at the other end of the cylinder, the valve or valves having sufficient travel and lap on the steam side to accomplish this.

I claim The valve cut off motion or operative mechanism, substantially as described, consisting of the two cams B and O, the two pairs of vibratory levers D and F, their common connectinglink G, andthe link H,joining and jointed to the shorter pair of such levers, such cams being applied to the shaft A, and the leversD being fulcrumed at or near their lower ends, and all being adapted in manner to operate essentially as represented.

JOHN WVARREN SARGENT.

Witnesses:

Gno. A. PERKINS, S. N. PIPER. 

